Bushing assembly

ABSTRACT

A bushing assembly installed in a sliding caliper, axially fixed rotatable disc, brake assembly in which the brake shoes transmit the brake torque to the caliper frame, which in turn transmits the brake torque to a fixed support member. The caliper assembly has a brake pad assembly including a brake shoe with ends extending laterally beyond the caliper frame and provided with a guide and support bushing assembly at each end, and a mounting plate operatively secured to the caliper frame. The mounting plate has laterally extending ends which each have a guide and support bushing assembly aligned with a similar arrangement in the noted brake shoe. Guide and support pins are fixed to the fixed support member and have portions extending through the bushing in the mounting plate and brake shoe ends so that the caliper is slidably supported and guided. Each bushing assembly includes an annular retainer having one end formed as an inwardly opening semi-torus and holding an elastomeric bushing engaging the associated pin in sliding relation, and the other end formed to lock the retainer in an aperture formed in the shoe or mounting plate end to which it is secured.

United States Patent [1 Brooks 1 Dec. 25, 1973 BUSHING ASSEMBLY [75]Inventor: Frank W. Brooks, Dayton, Ohio [73] Assignee: General MotorsCorporation,

Detroit, Mich.

[221 Filed: Aug. 10, 1972 [21] Appl. No.: 279,485

[52] US. Cl. 308/4 R, 16/2, 85/80 [51] int. Cl. Fl6c 1.7/00 [58] Fieldof Search 308/4 R, 15, 22,

Primary ExaminerManuel A. Antonakas Assistant ExaminerR. H. LazarusAtt0rneyW. E. Finken et al.

[57] ABSTRACT A bushing assembly installed in a sliding caliper, axiallyfixed rotatable disc, brake assembly in which the brake shoes transmitthe brake torque to the caliper frame, which in turn transmits the braketorque to a fixed support member. The caliper assembly has a brake padassembly including a brake shoe with ends extending laterally beyond thecaliper frame and provided with a guide and support bushing assembly ateach end, and a mounting plate operatively secured to the caliper frame.The mounting plate has laterally extending ends which each have a guideand support bushing assembly aligned with a similar arrangement in thenoted brake shoe. Guide and support pins are fixed to the fixed supportmember and have portions extending through the bushing in the mountingplate and brake shoe ends so that the caliper is slidably supported andguided. Each bushing assembly includes an annular retainer having oneend formed as an inwardly opening semi-torus andholding an elastomericbushing engaging the associated pin in sliding relation, and the otherend formed to lock the retainer in an aperture formed in the shoe ormounting plate end to which it is secured.

3 Claims, 5 Drawing Figures BUSHING ASSEMBLY The invention relates to abushing assembly and more particularly to one which slidably guides aplate member, in which the bushing assembly is mounted, on a guide andsupport pin. Inthe disclosed utilization of the bushing assembly, a discbrake caliper assembly is slidably mounted on circumferentially spacedpins extending parallel to the axis of rotation of a rotatable disc andover the disc outer periphery. The caliper assembly has guide andsupport bushing assemblies embodying the invention fitting over the pinsso that the caliper assembly is movable in axial directions relative tothe disc axis to permit brake actuation and adjustment for lining wear.The fixed support bracket to which the pins are fixedly secured isarranged to take the brake torque from the caliper frame, the torquehaving been transmitted from the brake pad assemblies to the caliperframe for this purpose. One side of the caliper assembly is providedwith a brake shoe assembly which also contains the guide and supportbushing assemblies fitting the pins. The other side of the caliperassembly includes a mounting plate similarly arranged to contain bushingassemblies fitting the pins. The bushing assemblies provide an effectiveand inexpensive mounting arrangement for the caliper, are easilyinstalled, and in one modification also easily removed, but only whenthe pin is first removed from the bushing assembly.

IN THE DRAWING FIG. 1 is an elevation view, with parts broken away andin section, of a disc brake assembly having bushing assemblies embodyingthe invention.

FIG. 2 is a cross-section view of the assembly of FIG. 1, taken in thedirection of arrows 2-2 of that FIG- URE.

FIG. 3 is a fragmentary view, with parts broken away and in section, ofthe assembly of FIG. ll taken in the direction of arrows 33 of thatFIGURE.

FIG. 4 is a fragmentary view, with parts broken away and in section, ofone of the bushing assemblies embodying the invention, as installed, andtaken in the direction of arrows 4-4 of FIG. 3.

FIG. 5 is a view similar to that of FIG. 4, and showing a modifiedbushing assembly embodying the invention.

The disc brake assembly It) includes an axially fixed rotatable disc 12,a fixed support bracket 14, and a caliper assembly 16. The caliperassembly is of the sliding type. The fixed support bracket is adapted tobe connected to a fixed portion of a vehicle, and the disc 12 is adaptedto be rotated with a vehicle wheel, as is well known in the art. Ageneral arrangement of this type is disclosed in U.S. Pat. No.3,628,639, issued Dec. 21, 197 l. The disc 12 has opposite frictionsurfaces 18 and 20 and an outer periphery 22. The fixed support bracket14 is mounted on one side of the disc 110 and has torque-receivingflanges or arms 24 and 26 which extend over the outer periphery 22 ofthe disc.

The caliper assembly 16 has a caliper frame 28 comprised of a bridgesection 30 extending over the disc outer periphery 22, an outboard leg32 extending parallel to and axially spaced from the disc frictionsurface l8, and an inboard leg 34 extending generally parallel to andspaced from the disc friction surface 20. Thus, the caliper frame isgenerally U-shaped in cross section. The bridge section 30 is providedwith edge surfaces 36 and 38 which are circumferentially spaced relativeto the disc and are arranged to engage the end surfaces 40 and 42,respectively, of fixed support member arms 24 and 26 intorque-transmitting relation as well as being relatively slidable indirections parallel to the axis of the disc.

The caliper assembly also includes an outboard brake pad assembly 44, aninboard brake pad assembly 46, a cylinder and piston assembly 48, amounting plate 50, and a caliper guide and support arrangement includingguide and support pins 52 and 54. The cylinder and piston assembly 48 isprovided with an adjuster mechanism 56 and a mechanical brake actuatingconstruction including a parking brake lever 58 and pin 60. The parkingbrake actuating mechanism and the adjuster mechanism 56 are disclosedand described in detail in U.S. Pat. application Ser. No. 131,936, filedApr. 7, 1971, entitled, Disc Brake Caliper With Integral Parking Brake,"now U.S. Pat. No. 3,688,875 and assigned to the common assignee. Othersuitable adjusters and manually actuated arrangements may be utilized asdesirable.

The cylinder and piston assembly 48 includes a cylinder body 62 whichextends through an aperture 64 of caliper frame leg 34 and is secured inplace in the aperture by a retainer 66. The inner wall of aperture 64and the mating outer surface 68 of the cylinder body 62 are respectivelyprovided with radially aligned grooves 70 and 72, which preferablyextend circumferentially completely about the surfaces. The groovescooperate to form an annular passage 74 which the wire-like retainer 66fills. The caliper frame leg 34 has a similarly sized passage 76 whichtangentially intersects passage 74 so that the retainer 66 can beinserted in place. The retainer arrangement is the subject of U.S. Pat.application Ser. No. 279,486, filed on even date herewith by me,entitled Retainer Assembly, and assigned to the common assignee.

The mounting plate 50 has an aperture 78 thorugh which the cylinder body62 is received, the cylinder body being provided with a shoulder 80which engages one side of the mounting plate 50, the other side of themounting plate engaging the outer surface 82 of caliper frame leg 34. Asuitable offset or lug 84 formed on cylinder body 62 fits in a matingportion of mounting plate aperture 78 to prevent circumferentialmovement of the mounting plate relative to the cylinder body.

The outboard pad assembly 44 includes a brake shoe 86 and brake liningfriction material 88. As best seen in FIG. 3, shoe 86 has bosses 90, onesuch boss being shown in FIG. 3, which extend away from lining 88 andinto recesses 92 formed in the caliper frame leg 32. Two such bosses andrecesses are preferably provided so that they precisely locate the brakepad assembly in relation to the caliper frame and transmit brake torquefrom the pad assembly to the caliper frame.

The brake shoe 86 has laterally extending mounting ends 94 and 96 whichextend circumferentially beyond the circumferentially spaced edges 36and 38 of the caliper frame 28. The mounting ends are respectivelyprovided with bushing assemblies 98 and 100. The mounting end 96 andbushing assembly 100 will be further described, it being understood thatthe mounting end 94 and bushing assembly 98 are similar. An aperture 102is formed in mounting end 96. The bushing assembly includes an annularbushing retainer 104 which extends through aperture 102, and anelastomeric bushing I86 which fits within an inwardly opening semi-torusI108 formed on one end of retainer 104.

The inner diameter of bushing 106 is smaller than the inner diameter ofthe retainer cylindrical center body section 110 and receives one end ofpin 54 therethrough in sliding and resilient supporting relation. Theother end of retainer 104 is formed as an axially opening semi-torus 112which is open toward the one end. In the installed position the twosemi-tori are on opposite sides of the shoe 86, and act to hold theassembly axially in place. Preferably the axial length of the centersection 110 is related to the thickness of shoe 86 so that a spring-likeretention of the assembly occurs, effectively preventing axial movementof the retainer 104 in aperture 102. The radially outer edge 114 ofsemitorus 112 engages the side of shoe 86 for this purpose. Eachsemi-torus has all parts thereof at least as large in diameter as theinner diameter of the center body section 110.

As best seen in FIGS. 3 and 4, the retainer 104 in one embodiment hasthe end forming semi-torus 112 and at least a part of the center bodysection 110 formed to provide axially extending resilient fingers 116,118 and 120 which are radially movable by bending to permit snapinstallation and removal of the bushing assembly in the aperture 102when pin 54 is not present in the assembly. Of course, this arrangementpresents the semi-torus 112 as a circumferentially interruptedsemitorus.

In the modification of the retainer assembly 200 shown in FIG. 5, thecylindrical center section and semi-torus 212 are uninterruptedcircumferentially. The retainer before installation has only thesemi-torus 108 pre-formed, the portion of the retainer later becomingsemi-torus 212 being an axial extension of the cylindrical centersection so that the retainer is inserted through aperture 102 and theend opposite the elastomeric bushing-receiving semi-torus is suitablyformed by spinning or by use of a shaped die to provide semitorus 212.Some methods of forming this semi-torus may result in one or morecircumferential interruptions, which will have no adverse effect on itsfunction. In both modifications, the term semi-torus is to be construedto be sufficiently broad to include other related shapes and not belimited to precisely semi-circular cross section. For example, thesemi-torus cross sections may be sections of ovals, ellipses, and othercurvilinear configurations or with parts having flat portions, so longas there is an area for mounting an annular elastomeric bushing in oneend and a retaining end of similar axially opening conformation on theother end.

The mounting plate 50 also has laterally extending mounting ends 122 and124 which are located on the other side of the disc from the brake shoemounting ends 94 and 96. The mounting plate mounting ends are providedwith bushing assemblies 126 and 128, respectively, which are constructedin the same manner as bushing assembly 100 and need not be furtherdescribed. The elastomeric bushing 130 of bushing assembly 128 receivesthe nut 132 of pin 54 in sliding and resilient supporting relation. Thebushing assemblies 98 and 126 similarly respectively receive pin 52 andits nut 134. The pins 52 and 54 are fixed to support bracket 14 bysuitable means, such as the thread and nut arrangement shown in FIG. 3,so that the pins extend axially parallel to the disc 10 and over thedisc outer periphery 22. The pins thereby support the caliper assembly16 and guide it in its sliding movements occurring during brakeactuation and lining wear.

The inboard shoe 136 of brake pad assembly 46 is operatively engaged bythe piston 138 on the side opposite its friction surface 20 so that whenthe pressure chamber 140, defined by cylinder body 62 and piston 138, ispressurized, piston 138 forces the brake pad assembly 46 into frictionalengagement with the disc friction surface 20. The pressure reaction inchamber 140 forces cylinder body 62 and caliper frame 28 in the oppositedirection, thereby moving the brake lining 88 of the outboard brake padassembly 44 into frictional engagement with the disc friction surface18. Any necessary sliding movement of the caliper assembly to accomplishthis brake actuation is accomplished by movement of the caliper asprovided for by the bushing assemblies. As the brake linings wear, thisaxial sliding movement permits maintenance of brake adjustment. Theadjuster mechanism 56 will operate to prevent an undesirable amount ofretraction of piston 138 upon brake release, thereby maintaining brakeadjustment. If the brake is manually actuated by rotation of parkingbrake lever 58, piston 138 is moved forwardly and the caliper frame isoppositely moved to engage the brake linings with their respective discfriction surfaces in braking relation. When the lever 58 is rotated torelease, the brake is released.

Bushing assemblies embodying the invention may be used effectively inother mechanisms than disc brake mounts. They provide effective, easilyinstalled, inexpensive and reliable means for resilient guide andsupport relative to a pin or rod, particularly in applications where thebushing assemblies are to be on plates.

What is claimed is:

l. A bushing assembly adapted to be removably installed in an aperturein a plate and to slidably guide a pin extending through the plate, saidbushing assembly comprising:

an annular retainer having a cylindrical center body section with oneend formed as an inwardly opening semi-torus and the other end formed asan axially opening semi-torus open toward said one end, each semi-torushaving all parts thereof at least as large in diameter as the innerdiameter of said center body section;

and an annular elastomeric bushing having an inner diameter less thanthe inner body diameter of said center body section and received in saidinwardly opening semi-torus and adapted to slidably engage the pinextending therethrough;

said axially opening semi-torus end being adapted to engage one side ofthe apertured plate and the outer surface of said inwardly openingsemi-torus being adapted to engage the other side of the apertured plateand retain said assembly in the plate aperture.

2. The bushing assembly of claim 1,

said other end and at least a part of said center body section beingformed to provide axially extending resilient fingers which are radiallymovable by bending to permit snap installation and removal of saidbushing assembly in the plate aperture in the absence of the pin.

3. The bushing assembly of claim 1,

said other end being formed to provide the axially opening semi-torus asa circumferentially uninterrupted semi-torus.

1. A bushing assembly adapted to be removably installed in an aperturein a plate and to slidably guide a pin extending through the plate, saidbushing assembly comprising: an annular retainer having a cylindricalcenter body section with one end formed as an inwardly openingsemi-torus and the other end formed as an axially opening semi-torusopen toward said one end, each semi-torus having all parts thereof atleast as large in diameter as the inner diameter of said center bodysection; and an annular elastomeric bushing having an inner diameterless than the inner body diameter of said center body section andreceived in said inwardly opening semi-torus and adapted to slidablyengage the pin extending therethrough; said axially opening semi-torusend being adapted to engage one side of the apertured plate and theouter surface of said inwardly opening semi-torus being adapted toengage the other side of the apertured plate and retain said assembly inthe plate aperture.
 2. The bushing assembly of claim 1, said other endand at least a part of said center body section being formed to provideaxially extending resilient fingers which are radially movable bybending to permit snap installation and removal of said bushing assemblyin the plate aperture in the absence of the pin.
 3. The bushing assemblyof claim 1, said other end being formed to provide the axially openingsemi-torus as a circumferentially uninterrupted semi-torus.